This is a very interesting and very sophisticated subject. Hopefully I can get the ball rolling with the following: With delta neutral offsetting positions, negative net gamma causes this to loose whenever the underlying moves, no matter what one does to adjust the deltas. On the other hand, delta neutral offsetting positions with positive gamma wins, only when the underlying moves, because the gamma increase has to exceed the theta decay which occurs when the stock doesn't move. Hopefully, over the next several days and weeks the above can be embellished with some actual examples. Bob